1. Field of the Invention
This invention relates to an ink jet recording apparatus provided with blower means, and particularly to an ink jet recording apparatus provided with means for positively blowing air to a recording area, and forming images on the surface of a recording medium by flying ink droplets.
The ink jet recording apparatus of the present invention covers an ink jet recording apparatus singly used or incorporated in or connected to an instrument such as a copying apparatus, a facsimile apparatus or a word processor, and all these recording apparatuses.
2. Related Background Art
Some of prior-art blower means are disposed around a carraige provided with an ink jet recording head and are moved with the recording head. For example, from U.S. Pat. No. 4,369,450 there is known a construction in which in an ink discharge area, air is blown in a direction similar to the direction of ink discharge and ink mist is sucked toward the carriage side. Conversely in U.S. Pat. No. 4,361,845, there is disclosed a construction in which ink mist is sucked by two suction ports located above an ink discharge area.
On the other hand, prior to these U.S. patents, U.S. Pat. No. 3,854,399 describes a construction in which air is applied to the printing area of a paper surface and a construction in which air is sucked, and discloses blower means fixed to an ink jet recording head of the continuous type.
Any of these is designed with a view to remove ink mist, but does not consider in detail the influence upon recording ink droplets themselves.
On the other hand, in Japanese Laid-Open Patent Application No. 62-218134 (U.S. application Ser. No. 319,878), there is shown a construction in which ink mist is sucked from both sides of a recording area and collected efficiently, but this neither gives consideration to the entire recording area. As regards the generation of such ink mist, in the ink jet recording of the on-demand type using the formation of bubbles by heat energy, much mist is generated by impact although the speed of ink droplets can be made high.
The present invention remarks the relation which has heretofore not been considered between the accuracy of shooting of recording liquid droplets and blower means for solving such problems as ink mist and condensation, and can achieve efficient collection of ink mist and prevention of condensation while accomplishing recording well.
Studies have been made while paying attention to the relation between ink mist adhering to the ink jet recording head and main recording ink droplets in order to reliably remove the ink mist in the entire recording area from the vicinity of the recording head to thereby prevent condensation without disturbing the recording ink droplets discharged from the ink jet recording head.
As a result, it has been found that the ink mist itself comprises minute drops separated from the final area of recording ink droplets and minute drops created by the rebound of the recording ink droplets occurring after the impact thereof against a recording medium such as paper and these irregularly move along a course differing from the course of the main recording ink droplets and that the size thereof is particularly irregular, i.e. under 1/20 of the size of the main recording ink droplets.
Also, ink jet recording apparatuses are divided broadly into the serial type and the full-line type, and in any of these types, if a suction stream or a supply stream by blast is formed in the gap between the recording head and the recording medium, at least a part of the record will be affected thereby. The pursuit of this has led to the discovery that the stream by the blast is varied in the recording area with a result that a turbulent flow is caused or there exists an area in which no effect of the blast is seen. This has been particularly conspicuous in the full-line type recorder.
On the other hand, in order to fixate ink shot onto a recording medium, there are constructions as disclosed in Japanese Laid-Open patent Application No. 54-156536 and Japanese Laid-Open Patent Application No. 54-156537 wherein hot air is utilized to dry the ink on the recording medium, and constructions as disclosed in Japanese Laid-Open Patent Application No. 62-130863 and Japanese Laid-Open Patent Application No. 62-130864 wherein the recording medium itself is heated to thereby dry and fixate the ink.
However, in the prior-art fixating means of the type as described above which utilizes hot air to dry the ink on the recording medium, particularly when it is carried out in a low-temperature atmosphere, a sufficient effect is not obtained and the heat of the hot air is taken away by the surrounding bodies kept at a low temperature and the recording medium, and satisfactory fixation has been difficult.
Also, the fixating means of the type in which the recording medium is heated by a heater to thereby fixate the ink has suffered from the inconvenience that where use is made of a recording sheet such as bond paper readily absorbing moisture, the interior of the apparatus is filled with steam provided by the moisture evaporating from the surface of the paper and the moisture evaporating from the recording ink and the steam becomes saturated and is condensed on the ink discharge surface of the recording head to cause non-discharge or twisted discharge of the ink. Particularly as regards the latter point, a greater attempt to keep the spacing between the ink discharge surface of the recording head and the recording medium narrow to improve the quality of recording has led to a more remarkable tendency toward condensation, and has sometimes resulted even in the impossibility of recording.
According to the inventor's studies, it is inferred that the generation of steam by fixation brings about the above-noted inconvenience due to the formation of water drops smaller than or equal in size to the aforedescribed mist and therefore, the inventor has pursued to prevent the inconvenience in fixation by blower means capable of achieving the prevention of the ink mist.